Immobilization devices such as casts, splints, braces and stiffening apparatus are used to impart a desired position to a supported portion of the body or to immobilize the supported portion relative to other parts of the body. Traditionally, plaster casting materials have been used because they are very low cost. However, plaster casting materials are heavy and cannot be cleaned or easily removed. Recently, plaster casting materials have been replaced by synthetic casting materials which are lighter in weight and can be cleaned but have a rough exterior surface and are still relatively heavy and bulky.
Further, both plaster of paris and synthetic resin casts require skill in wrapping techniques and there are areas of the cast where folds are unavoidable, for example in the thumb web space. Wrapped casting materials do not give as even a pressure on the body part as thermoplastic material in fracture bracing applications due to the overlaps of the casting material.
Thermoplastic materials such as those described in U.S. Pat. No. 4,240,415, are now being used for forming casts and braces and other immobilization devices. These thermoplastic materials can be produced in extruded sheets which, when brought to a melt point (50.degree. C. to 100.degree. C.), can be molded and manipulated to conform to and shape around a body part, such as a limb, and than allowed to cool to hardness. These materials can also be reheated, brought back to their original shape and then remolded into a different shape. Compared to other casting materials, the thermoplastic materials described in U.S. Pat. No. 4,240,415 provide many advantages including simplicity of use and ease of cleaning.
It is also often necessary that a cast or other immobilization device be removed for medical consultation or exercise by a therapist and then put back on the patient. The plaster and synthetic material casts cannot be removed intact and put back on the patient.
U.S. Pat. No. 4,060,075 describes a splinting system which is formed from a transformable material imbedded in a fabric that can include a fastener such as a zipper or a pile and loop material. In this splinting system, a two component plastic is mixed and molded in a double walled fabric that is then installed around the body part before the plastic mixture hardens. It is difficult to obtain an even cast thickness and cast surface with this splinting system and when the cast hardens it is very stiff and has no elasticity. Further, the cast cannot be reused and cannot be perforated in order to provide for ventilation.
European patent application No. 401 883 describes a thermoplastic immobilization device made from a thermoplastic extrudable molding material that is surrounded by a fabric that has a zipper on two opposite sides of the cast or splint. A commercial embodiment of EP 401,883 is known as ORFZIP which consists of a thermoplastic material within a stockinette type fabric with a zipper. The device is vacuum packed in plastic in order to prevent the stockinette from getting wet when melting the thermoplastic material. The vacuum packed device is placed in water at a temperature required to soften the thermoplastic material so that it can be molded. Once the plastic packaging is opened, the cast cannot be reworked without getting the stockinette wet or the risk of burning the fabric with a heat gun. Also, the supple material or stockinette type fabric has a tendency to detach from the thermoplastic material and bunch up in areas which are stretched and molded, which causes potential pressure problems to the patient when the cast is in place. Further, the thermoplastic material is very sticky when softened which makes molding difficult.
The present invention seeks to remedy the aforementioned problems and drawbacks of the currently available immobilization devices. The invention resides in the combination of parts set forth in the specification and defined by the claims and provides a pre-cut thermoplastic immobilization apparatus with a directly attached fastener that allows the apparatus to be reapplied after removal and to be placed directly into a heat transfer area having the temperature of between 50.degree. C. to 100.degree. C. for causing the apparatus to be pliable.